The present invention relates to dumbbells, adjustable dumbbells, and more particularly to light weight dumbbells or light weight adjustable hand weights having specific ergonomic shapes that allow for the centering of weight in the palm of the hand, and interlocking features that allow for the ease of combination of units during an aerobic exercise to achieve a specific desired weight and intensity of workout.
Moreover, the present invention also relates to worn devices that are intended to track heart rates, steps or strides, body movements, force and exertion of movement with held weight, and calories burned per hour through the use of: heart rate monitors, pedometers, gyroscopes, accelerators, and other sensors.